1. Field of the Invention
The present invention relates to an apparatus for and method of ejecting ink to print images or characters.
2. Description of the Related Art
A typical actuator used for control of ink ejection in the inkjet printer has a plurality of ink chambers and a plurality of piezoelectric elements. This actuator is mounted on a head (printer-head). The piezoelectric elements correspond to the ink chambers, respectively. By expansion and restoring (shrinkage) of the piezoelectric elements, the pressure is applied to the ink in the respective ink chambers. The ink chambers communicate with the corresponding ink ejecting holes, respectively. When the pressure is applied, the ink is ejected from the ink chambers to the outside through the ink ejecting holes. The ink ejecting holes are formed on a nozzle plate, which is attached to the actuator. These ink ejecting holes are arranged in the directions of conveyance of recording papers and movement of the head.
When printing, certain ink chambers are selected from among all of the ink chambers, depending on image data to be printed or resolution. Namely, when printing, the ink chambers that actually eject ink are only selected. Then, the volume of the selected ink chambers is only changed by the expansion and shrinkage of the piezoelectric elements. Therefore, the internal pressure of the selected ink chambers is only controlled. Accordingly, the ink is supplied only into the selected ink chambers, and ejected only from the ink ejecting holes corresponding to the selected ink chambers.
However, the ink is supplied though a common ink channel to the ink chambers, respectively. Therefore, one ink chamber and another ink chamber are connected each other through this ink channel. As a result, when the internal pressure of the selected ink chamber is changed by the distortion of the piezoelectric elements, the change of the pressure is propagated through the ink channel as a pressure wave, and reaches other ink chambers, i.e., non-selected ink chambers. As a result, the ink in the non-selected ink chambers leaks to the outside through the corresponding ink ejecting holes. The leakage of the ink can disturb a shape of a meniscus of the ink in the ink ejecting holes. The disturbance of the meniscus causes undesirable changes of the ejecting direction of the ink or impossibility of the ink ejection.